This is a study that followed 931 substance using women who either received traditional services or traditional services plus a recovery coach. The study found that the use of recovery coaches in child welfare significantly decreases the risk of substance exposure at birth.
Ryan, J.P., Choi, S., Hong, J.S., Hernandez, P., Larrison, C.R. (2008). Recovery coaches and substance exposed births: an experiment in child welfare. Child Abuse and Neglect. 32(11), 1072-1029.